Locked-in syndrome is a neurological condition that features paralysis or a complete lack of movement of all the voluntary muscles in the different parts of the body, the only exception being the muscles that control the movement of the eye. It is a very rare disorder.

Some of the possible causes that may result in the disorder are drug overdose, extreme trauma or injury to the brain, diseases that destroy or damage the myelin sheath that covers the nerve cells and diseases that affect the circulatory system.

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Patients of locked-in syndrome are able to think and judge, which means that they are conscious and not in coma. However, such individuals cannot move or speak leaving them completely paralytic and mute. Individuals with locked-in syndrome may be able use the eye movements to communicate with others.

It is not possible to effectively predict the prognosis for locked-in syndrome. Some patients may be able to regain a few brain functions, but such cases are very rare. Also, any chance of motor control recovery is extremely restricted. Most of the studies conducted indicate that aggressive and early treatment of the disorder can best improve the chances of a limited recovery.

Types of Locked-in syndrome and its symptoms

Locked-in syndrome has been categorized into three different types by researchers. They are as follows:

Classic locked-in syndrome: The symptoms include anarthria and quadriplegia. The affected individuals retain their consciousness as well as vertical movement of the eyes.

Incomplete locked-in syndrome: The symptoms are similar to that elicited by classic locked in syndrome. However, in addition to preserved vertical eye movements, the affected individuals may also retain a weak ability to move their hands or arms. On rare occasions, the patients may also be able to make sounds such as groans or cry or be able to move the muscles of the face.

Total locked-in syndrome: The symptoms include complete paralysis with no control over the eye movements as well. The affected individuals cannot communicate in any way, but do retain complete consciousness.

Individuals affected by either classic or total locked-in syndromes may sometimes recover to the ‘Incomplete’ form of the disorder. However, it is very rare that the patients can regain complete control over their voluntary muscles, for the rest of their lives.

Individuals who develop locked-in syndrome due to a stroke may show several symptoms such as dizziness, headaches, hemiparesis and vertigo. Such signs and symptoms generally tend to occur a few days prior to the onset of the disorder. However, it is also important to note that some individuals may suffer from such premonitory symptoms for weeks and months before the development of locked-in syndrome.

Some of the general symptoms of locked-in syndrome include:

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Paralysis of the tongue, face and pharynx caused due to paralysis of the nerves VII, IX, X and XII in the brain. This can result in loss in the ability to talk or make sounds as well as swallowing difficulties. Another symptom is bilateral horizontal gaze paresis

Individuals affected by locked-in syndrome due to a pontine lesion, though, are able to blink and make vertical movements of the eye

Causes of Locked-in syndrome

Locked-in syndrome is a very rare neurological condition which is caused due to primary vascular or damage of the brainstem. Such trauma generally corresponds to a lesion of the ventral pons or may be related to an injury to or blockage of the basilar artery. Any form of severe injury to the brainstem can lead to a direct contusion of the brainstem or a dissection of the vertebra-basilar axis.

Some other causes of locked in syndrome include the following:

Penetration of the ventral pons by certain brain tumors

The presence of diseases such as multiple sclerosis that lead to destruction of the nerve cells as well as damage to the myelin sheath that affects the pons.

Chronic case of hypoglycemia

Hemorrhage that begins in the pons or commences elsewhere and penetrates the pons

An overdose of drugs like neuromuscular blockingmedications can also cause locked-in syndrome

Ischemia which results due to hypoxic episodes or by hypotensive events or by basilar artery occlusion

Locked-in syndrome may also occur as a symptom of the final stages of amyotrophic lateral sclerosis

Cases of temporary locked-in syndrome can be caused due to extreme instances of chronic inflammatory demyelinating polyneuropathy or due to the intake of certain medications.

Locked-in Syndrome Treatment

Since locked-in syndrome is very rare, the available data is very limited and hence the treatment for the condition is not known as yet. Currently, there are no standard procedures that one needs to follow to treat the condition, neither is there any known cure.

Some of the paralyzed muscles may be reactivated by the use of a therapy known as functional neuromuscular stimulation which involves the stimulation of muscle reflexes by employing electrodes.

Communication can be made possible via the use of various instruments and devices.

All symptoms of locked-in syndrome are supported and treated as per individual cases.

Almost ninety percent of the individuals affected by locked-in syndrome die within the first 4 months of the condition; some may live for a few years, while a very rare few may spontaneously have a complete recovery.